Detect CVE-2025-20393 — Cisco Multiple Products Improper Input Validation (KEV) in Splunk
Detects exploitation attempts targeting CVE-2025-20393, an improper input validation vulnerability (CWE-20) affecting Cisco Multiple Products. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active in-the-wild exploitation. Attackers may leverage this flaw to bypass security controls, execute unauthorized commands, or gain elevated access to affected Cisco appliances.
MITRE ATT&CK
SPL Detection Query
index=network OR index=cisco sourcetype=cisco:* OR sourcetype=syslog
| eval request_lower=lower(uri_path)
| where match(request_lower, "(\.\./|%2e%2e%2f|%252e|;%00|null%00|\.%00|\/cgi-bin\/|exec=)")
OR match(uri_path, "(?i)(CVE-2025-20393)")
OR (vendor="Cisco" AND match(message, "(?i)(invalid input|input validation failed|malformed request|unexpected token)"))
| eval attacker_ip=coalesce(src_ip, src)
| eval target_host=coalesce(dest_host, dest_ip, host)
| stats count as attempt_count, values(uri_path) as observed_paths, earliest(_time) as first_seen, latest(_time) as last_seen by attacker_ip, target_host, sourcetype
| where attempt_count > 1
| sort -attempt_countDetects patterns consistent with CVE-2025-20393 exploitation in Cisco product logs, looking for path traversal, null byte injection, and input validation failure messages aggregated by source IP and target host.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Automated vulnerability scanners performing routine compliance checks
- Application developers testing API endpoints with unusual input during development
- Corrupt log entries from misconfigured Cisco appliance syslog forwarders
Other platforms for CVE-2025-20393
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Path Traversal Probe Against Cisco SMA Interface
Expected signal: HTTP request log entry with URI containing '../' sequences recorded in Cisco SMA access log; network flow record from test host to Cisco appliance on port 443
- Test 2Null Byte Injection Input Validation Test
Expected signal: HTTP request containing '%00' in query string logged by network proxy or Cisco appliance; potential error response indicating input validation failure
- Test 3Automated Exploitation Pattern Simulation with Repeated Requests
Expected signal: Ten sequential HTTP requests with encoded path traversal sequences from same source IP within 10 seconds, logged across Cisco access logs and network flow telemetry
Unlock Pro Content
Get the full detection package for CVE-2025-20393 including response playbook, investigation guide, and atomic red team tests.